The Supreme Court upheld a key part of Arizona's crackdown on illegal immigrants on Monday, rejecting the Obama administration's stance that only the U.S. government should enforce immigration laws in the United States.

The nation's highest court, in an opinion by Justice Anthony Kennedy, upheld the state law's most controversial aspect, requiring police officers to check the immigration status of people they stop.

But in a split decision, the justices also ruled that the three other challenged provisions went too far in intruding on federal law, including one provision that makes it a crime for illegal immigrants to work and another that requires them to carry their documents.

Arizona, on the southwest border with Mexico, two years ago became the first of a handful of U.S. states to pass laws aimed at driving illegal immigrants out, including requiring police to check the immigration status of anyone detained and suspected of being in the country illegally.

The battle over the law goes to the heart of a fierce national debate between Democrats and Republicans over what to do with the roughly 11 million illegal immigrants in the country.

Critics have said the Arizona law could lead to ethnic and racial profiling of the fast-growing Hispanic population in the United States. Hispanics are the largest U.S. minority group.

Other parts of the Arizona law require immigrants to carry their papers at all times; ban illegal immigrants from soliciting work in public places; and allow police to arrest immigrants without a warrant if an officer believes they have committed a crime that would make them deportable.

How did Americans feel about the Arizona immigration law before the Supreme Court ruled?

A CNN/ORC poll conducted on May 29-31 found that 75% were in favor of it while 2% opposed it.

CNN's Kate Bolduan, clarifying the ruling, said of the provision that was upheld: "If they suspect you have broke a law that is already on the books, they can check your immigration status" if theres reasonable suspicions a person is in the country illegally.

[Updated at 10:26 a.m. ET] The Court ruled largely in favor of the U.S. government, striking down three parts of the Arizona immigration law, but the Court did uphold one the most notorious provisions: A requirement that local police officers check a person's immigration status while enforcing other laws if "reasonable suspicion" exists that the person is in the United States illegally.

The question now is can that single provision stand on its own, or does the court action mean Arizona has to go back to the drawing board on their immigration law.

[Updated at 10:23 a.m. ET] CNN's Senior Political Analyst David Gergen weighs in on the Arizona immigration ruling:

“The court apparently has said, ‘No, you can’t do that.’ Those are centralized powers and you can’t step in.”

The Supreme Court has issued 5-3 decision in favor of U.S. government, with Justice Kennedy saying that the government has significant power to regulate immigration and while Arizona may have signifacnt frustrations they may not have policies that undermine federal law.